1. Field of the Invention
The present invention concerns a stirring type reactor, e.g., stirred tank, for viscous materials, particularly a reactor for efficiently carrying out reactions under stirring, of materials having low and moderate viscosity, for example, not higher than 10,000 centipoises.
2. Description of Prior Art
Hitherto, as a stirring type apparatus for viscous materials, a stirring vane having multiple blades, one end of which is secured on a rotating shaft and the other end of which extends in the radial direction of the interior of the stirring vessel, has been proposed.
In the stirring vessel, the viscous material is liable to be stirred along a convection current of the liquid caused by revolution of the vane and a shearing force created in the space between the inner wall of the vessel and the stirring vane.
Thus, generally the stirring vessel provided with the stirring vane having multiple blades is advantageously used since a strong shearing force is easily generated. For example, a specific combination of multiple vanes which are provided on the rotating shaft at different heights, and baffle plates which are provided on the inner wall of the vessel at different heights, the positions of the vanes being different than the positions of the baffle plates, has been widely adopted as well.
In the prior art stirring vessel, when the uppermost vane is positioned at around the gas-liquid interface, a vibration is liable to be caused in the vessel and stirring vanes and the vessel thereby suffers from difficulty in speed-up of revolutions. On the other hand, when the uppermost vane is positioned away from the gas-liquid interface, a so-called dead spot appears in the area of the gas-liquid interface and no stirring occurs at or near the surface of the solution.
Accordingly, the prior art stirring reactor has disadvantages that efficiency of a stirring reaction cannot be improved and stirring is required for a long period of time due to insufficient stirring.